LED driver apparatus

Abstract

A Light Emitting Diode (LED) driving apparatus and a method of driving a LED backlight unit are provided. An LED driving apparatus includes: an input unit configured to receive a dimming signal, an extension unit configured to extend ON time of the inputted dimming signal, an LED driving unit configured to drive an LED array using the extended dimming signal, and a detection unit configured to detect a degradation of the LED array by measuring a forward voltage between the LED array and the LED driving unit.

What is claimed is: 
     
       1. A Light Emitting Diode (LED) driving apparatus, comprising:
 an input unit configured to receive a dimming signal; 
 an extension unit configured to extend an ON time of the dimming signal; 
 an LED driving unit configured to drive an LED array using the extended dimming signal; and 
 a detection unit configured to detect a degradation of the LED array by measuring a forward voltage between the LED array and the LED driving unit, 
 wherein the detection unit is configured to detect the degradation by measuring the forward voltage at a time of a declining edge of the dimming signal. 
 
     
     
       2. The LED driving apparatus of  claim 1 , wherein the extension unit comprises:
 a delay unit configured to delay the dimming signal; and 
 an OR gate configured to receive the dimming signal and the delayed dimming signal, and output the extended dimming signal. 
 
     
     
       3. The LED driving apparatus of  claim 2 , wherein the delay unit is configured to delay the dimming signal by 100 ns to 1000 ns. 
     
     
       4. The LED driving apparatus of  claim 1 , wherein in response to a substantially entire portion of the dimming signal being duty signal, a clock signal having a preset frequency is provided to the detection unit instead of the dimming signal. 
     
     
       5. The LED driving apparatus of  claim 4 , wherein the extension unit comprises a multiplexer configured to provide one of the dimming signal and the clock signal to the detection unit, based on the duty cycle of the dimming signal. 
     
     
       6. The LED driving apparatus of  claim 4 , wherein the clock signal is used to generate a PWM signal to adjust a driving voltage of the LED array. 
     
     
       7. The LED driving apparatus of  claim 1 , wherein LEDs in the LED array are in a working state when a first preset voltage is less than the measured forward voltage and a second preset voltage is greater than the measured forward voltage, and
 the detection unit is configured to 
 determine the LED array is in an open state in response to the measured forward voltage being smaller than the first preset voltage, and 
 determine the LED array is in a shorted state in response to the measured forward voltage being larger than the second preset voltage. 
 
     
     
       8. The LED driving apparatus of  claim 1 , wherein the detection unit comprises:
 a first comparator configured to compare the measured forward voltage and a first preset voltage to determine whether the measured forward voltage is smaller than the first preset voltage; 
 a second comparator configured to compare the measured forward voltage and a second preset voltage to determine whether the measured forward voltage is larger than the second preset voltage; 
 a first determining unit configured to determine whether the LED array is in an open state depending on an output from the first comparator, when the dimming signal is at a declining edge; and 
 a second determining unit configured to determine whether the LED array is in a shorted state depending on an output from the second comparator, when the dimming signal is at a declining edge. 
 
     
     
       9. The LED driving apparatus of  claim 8 , wherein the first determining unit comprises
 a first inverter configured to
 invert the dimming signal, and 
 output a result; and 
 
 a first data flip-flop configured to 
 receive the inverted dimming signal from the first inverter as a clock signal, and
 receive the output from the first comparator as a data signal, and the second determining unit comprises 
 
 a second inverter configured to
 invert the dimming signal, and 
 output a result; and 
 
 a first data flip-flop configured to 
 receive the inverted dimming signal from the second inverter as a clock signal, and 
 receive the output from the second comparator as a data signal. 
 
     
     
       10. The LED driving apparatus of  claim 8 , wherein LEDs in the LED array are in a working state when the first preset voltage is less than the measured forward voltage and the second preset voltage is larger than the measured forward voltage. 
     
     
       11. A Liquid Crystal Display (LCD) comprising:
 a liquid crystal panel; and 
 an LED driving apparatus of  claim 1 . 
 
     
     
       12. The LED driving apparatus of  claim 1 ,
 wherein the detection unit is configured to detect the measured forward voltage is greater than a first predetermined voltage in response to receiving a declining edge of the dimming signal. 
 
     
     
       13. The LED driving apparatus of  claim 1 ,
 wherein the detection unit is configured to detect the measured forward voltage is less than a second predetermined voltage in response to receiving a declining edge of the dimming signal. 
 
     
     
       14. A method of driving an LED backlight unit, the method comprising:
 extending an ON time of a dimming signal; 
 driving an LED array using the extended dimming signal; and 
 detecting a degradation of the LED array by measuring a forward voltage between the LED array and the LED driving unit at a time of a declining edge of the dimming signal. 
 
     
     
       15. The method of driving an LED backlight unit of  claim 14 , wherein the dimming signal is received from an external source. 
     
     
       16. The method of driving an LED backlight unit of  claim 14 , wherein the extending comprises:
 delaying the dimming signal, 
 receiving the dimming signal and the delayed dimming signal at an OR gate, and 
 outputting the extended dimming signal. 
 
     
     
       17. The method of driving an LED backlight unit of  claim 16 , wherein the dimming signal is delayed by 100 ns to 1000 ns. 
     
     
       18. A Light Emitting Diode (LED) driving apparatus, comprising:
 an input unit configured to receive a dimming signal; 
 an extension unit configured to extend an ON time of the dimming signal; 
 an LED driving unit configured to drive an LED array using the extended dimming signal; and 
 a detection unit configured to detect a degradation of the LED array by measuring a forward voltage between the LED array and the LED driving unit, 
 wherein the detection unit is configured to: 
 receive a clock signal having a predetermined frequency instead of the dimming signal in response to the dimming signal having a duty cycle greater than a predetermined threshold, and detect the degradation by measuring the forward voltage at a time of a declining edge of the clock signal.